A jig-saw puzzle consists of several irregular interlocking pieces which when properly fitted together form a picture or design. To facilitate assembly, the many pieces are spread out face-up on a flat surface. By comparison of their shapes and design, the individual pieces can be assembled to form the completed picture. Often, different portions of the puzzle are assembled simultaneously.
A puzzle, if not assembled at a single sitting, is often left unattended. The inventor, in observing his mother assemble many puzzles, became aware of the number of perils facing the partially completed, unattended puzzle. Small children or household pets, attracted by the brightly colored pieces, may knock the partially completed puzzle off the work surface, scattering the pieces across the floor. Similarly, an accidental bumping of the work surface may cause pieces to be disturbed.
An additional problem arises when assembling a puzzle on an open surface. When the exterior parameters of the completed puzzle are undefined on the work surface, it is difficult to position the partially assembled portions in proper relationship to one another. When the exterior parameter is defined on the work surface, it is possible to place the various partially completed portions in relationship to that defined parameter and, thus, in proper relationship to one another.